Smoking and bladder cancer risk is higher than previously reported, and the risk for bladder cancer in women smokers is the same as that of men.
Over 350,000 people are diagnosed with bladder cancer every year globally, which includes over 70,000 each year in the US. Research has proven the risk for bladder cancer from smoking in both women and men, with earlier research revealing that current cigarette smoking triples risk for bladder cancer in comparison to never having smoked. Cigarette composition has however changed in the past 50 years, resulting in a reduction in nicotine and tar concentrations in cigarette smoke, but also to an apparent increase in the concentration of certain carcinogens, which includes beta-napthylamine, a recognized bladder carcinogen.
Researchers analysed data that they collected from almost 500,000 people. 627 women and 3,896 men were newly diagnosed with bladder cancer during the course of follow-up. Risk for bladder cancer from smoking was significant in both genders. In comparison to never having smoked, current and former smokers had increased risk for bladder cancer in both women and men. Analysis of the data showed that former smokers had a 2.2 times increased bladder cancer risk and that the risk was about 4 times higher for current smokers in comparison to never having smoked. The summary risk estimate for current smoking in 7 earlier studies was 2.94.
One factor that could have strengthened the association between cigarette smoking and bladder cancer includes changes in the constituents of cigarette smoke (like increased concentrations of beta-napthylamine).
These results support the hypothesis that the risk for bladder cancer from smoking has increased with time in the US, possibly a reflection of changing cigarette composition.